(a) Field of the Invention
The present invention relates to a power supply. More specifically, the present invention relates to a power supply for supplying the power to the night vision device and using most capacity of the battery by selecting the supply voltage according to a predetermined voltage.
(b) Description of the Related Art
In general, a night vision device is used for military or police purposes in the night or darkness. The night vision device amplifies light to form images, and allows a user to easily discriminate things in the darkness. In detail, it includes a lens for focusing on a desired object, and an image intensifier for absorbing the surrounding light, converting the light into electronic patterns, changing them into light discernible by an observer, and transmitting the light to a photosensitive screen.
The above-configured night vision device uses a battery because of its portability, and the battery supplies power to the image intensifier and other circuits. A power supply of the night vision device uses a battery of 1.5 to 3V (volts).
In the case of using a 3V -battery, the night vision device operates in a battery voltage range of from 1.9 to 3.0V, and the battery must be changed if its voltage falls below 1.9V since the low voltage cannot drive the night vision device. Therefore, unnecessary battery waste occurs, since the battery cannot be used even though it has some residual voltage.
Additionally, in the case of using the 3V -battery, two 1.5V batteries are coupled to generate the voltage of 3.0V enabling the operation of the night vision device. However, the usage of 1.5V-batteries increases current consumption to thus reduce usage time of the night vision device, accordingly increasing battery waste caused by frequent changes of the batteries.
Further, conventional power supplies used for the night vision device support only one 1.5 battery or two 1.5V batteries, and hence, efficient battery usage is not possible. In addition, a long use of the image intensifier in the high light area may damage the image intensifier, and may mistakenly drive the same to increase the battery consumption.